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Is there a problem cutting the power to an operating VFD?

Mark Rand

Diamond
Joined
Jul 9, 2007
Location
UK Rugby Warwickshire
The other way to do it is with a contactor on the VFD output. That has got the disadvantage that it would need to be three pole.

Presumably you are planning to use the same single pole contactor to switch both the single phase motor and the VFD?
 

kustomizer

Titanium
Joined
Aug 17, 2007
Location
North Fork Idaho
The other way to do it is with a contactor on the VFD output. That has got the disadvantage that it would need to be three pole.

Presumably you are planning to use the same single pole contactor to switch both the single phase motor and the VFD?

Well, I am in the thinking/planning phase on the electrical. I am getting close to being able to run the machine manually then I will dive into that part, I have plenty of contactors on hand but would like to use as few as possible and would like the machine to be completely off when the timer runs down.
 

Tony Quiring

Titanium
Joined
Nov 5, 2008
Location
Madera county california usa
Many options here.

Mist VFD will not like plug pulled while running so design to NOT do that.

However, you can add a suitable contactor on line side for emergency use.

You can use time delar relays, these are standard off the shelf items that connect just like normal ones but also have a "control" line that causes them to do their action.

We use one in our bobcat for glow plug, instead of push and hold we tap and relay holds for 30 seconds, easy.

You can use simple relay to provide controlled outputs to control contactor for 1 phase motor and also VFD logic control.

Very simple.

Sent from my SM-G781V using Tapatalk
 

neilho

Titanium
Joined
Mar 23, 2006
Location
Vershire, Vermont
I believe so, is there a reason for it to remain on when it is not in use?

Not that I can think of. Save a bit of power, too.

I'm an energy conservation freak that unplugs every wall wart in my superinsulated shop when it's not in use, but realize I'm an anomaly in this world. Glad to hear someone else is thinking that way, even though it may be for different reasons.

Offhand, it seems a relay with electrical interlock supplying power to the VFD could work. The relay could be activated with a momentary switch and after the timed event has happened, turned off by the VFD itself. If I'm thinking of this correctly, the VFD would need an auxiliary input for the timer and an auxiliary NC output to control the relay.

Of course, simpler to just cut power to the VFD with a timed relay, IF the VFD could withstand it safely.

My apologies if this has already been suggested - I haven't read the thread completely.
 








 
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